Long-Term Debt (Details) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Long-term debt obligation
Total debt	$ 104,125,000	$ 110,250,000
Less current maturities	12,250,000	12,250,000
Total long-term debt	91,875,000	98,000,000
2010 Revolving Credit Facility, due August 12, 2013
Long-term debt obligation
Basis of interest rate	LIBOR	LIBOR
Total debt	0	0
Remaining borrowing capacity	60,500,000
2011 Term Loan Facility, due August 16, 2016
Long-term debt obligation
Basis of interest rate	LIBOR	LIBOR
Total debt	$ 104,125,000	$ 110,250,000
Effective rate of interest (as a percent)	2.20%